Improvised explosive devices (“IED”) are a significant cause of fatalities for U.S. service personnel in Iraq and Afghanistan. They are also a concern in screening materials for airport security. The present invention represents various approaches to TED detection. This approach could also be applied to a device for screening liquid containers, such as water bottles at airports.
Other explosive detection devices may include: ion mobility spectrometers as discussed in U.S. Pat. No. 7,098,672 to Belyakov, hereby incorporated by reference; use of ultraviolet, visible, or infrared light to identify explosives as discussed in U.S. Pat. Pub. No. 2007/0212791 to Hummel, hereby incorporated by reference; use of near infrared spectroscopy to detect —OH, —CH, or —NH bonds as discussed in UK Pat. Pub. No. GB2297377A to Burrows, hereby incorporated by reference; use of photoluminescence for the detection of TNT as discussed in Buzzle.com (web article, “Photoluminescence spectroscopy: New technique for detecting explosives” by Vishwas Purohit of Oct. 11, 2004 at http://www.buzzle.com/editorials/10-11-2004-60363.asp), hereby incorporated by reference; use of THz-radiation for identification of concealed objects as discussed in U.S. Pat. Pub. No. 2007/0228280 to Mueller, hereby incorporated by reference; use of quadrupole resonance detection for detecting explosives as discussed in PCT Pub. No. WO2007/100761 to Schiano, hereby incorporated by reference; and use of ultraviolet light for detection of explosives as discussed in U.S. Pat. Pub. No. US2007/0221863 to Zipf, hereby incorporated by reference.
None of the past references use NIR spectroscopy to detect certain chemical groups indicative of explosive devices, namely carbonyl and nitro groups. Specifically, the Hummel reference does not mention the use of near infrared spectroscopy with the detection of explosives. Near infrared detection (“NIR”) is different from infrared (“IR”) detection. NIR may include wavelengths of about 800 nm to about 2500 nm and IR may include wavelengths of about 2500 nm to about 15,380 nm and they can require different equipment and sample handling techniques for each. Further, the Hummel reference describes use with Differential Reflectance Spectra, which may scan a wavelength region at two different and spaced apart locations on the sample.
Further, the Burrows reference does not mention the detection of carbonyl or even nitro groups of explosive devices. Burrows may have found that detection of —OH, —CH, or —NH groups are easily accessible by use with a tungsten-halogen lamp (e.g., a light bulb). Burrows did not look at longer wavelengths of the NIR spectrum since at that time, no-one was aware that use with longer wavelengths, e.g., use with NIR at 2200 nm, might be useful for explosive detection, namely nitro and carbonyl groups of explosives. The present invention, in embodiments, entails use with specific NIR optics to achieve a desired wavelength region in order to detect nitro and carbonyl groups.